In recent years, much research has been directed at developing fuel-cell vehicles equipped with fuel cells for practical use. One example is a vehicle in which a fuel in a gaseous state (“fuel gas”) and oxidant gas are supplied into a fuel cell where these gases (reactant gases) are electrochemically reacted to obtain a driving output. Because air can be used as the oxidant gas in this vehicle, it is not necessary to store an oxidant gas inside the vehicle, but only the fuel gas composed of hydrogen. As a method for filling the fuel gas into the vehicle, a similar method as for a gasoline vehicle may be used. Specifically, the fuel gas may be supplied into a fuel gas container provided inside the vehicle by inserting a fuel gas filler nozzle provided at an external fuel gas filling station into a fuel gas filler opening disposed on the vehicle.
For example, Japanese Patent Publication JP 2003-291667 A describes use of a conventional technique for fueling a fuel-cell vehicle with a fuel gas. As shown in FIG. 6, in a conventional technique for fueling a fuel-cell vehicle 11 with a fuel gas, a fuel gas filler nozzle 13 of an external fuel gas supplying device 12 (that is, provided separately from the fuel-cell vehicle 11) is inserted into a fuel gas filler opening 14 of the fuel-cell vehicle 11. Then, fuel gas (hydrogen gas) is transferred into a fuel gas tank 15, which is a tank for storing a fuel gas (hydrogen gas), via the fuel gas filler opening 14 from the fuel gas filler nozzle 13. Further, a grounding line portion 16 of the fuel gas supplying device 12 is connected to the fuel-cell vehicle 11. The grounding line portion 16 is grounded at the fuel gas supplying device 12 to discharge static electricity from the fuel-cell vehicle 11.
As shown in FIGS. 7 and 8, a recess 21 which is concave from the outer surface of a vehicle body 20 is provided on a rear side portion of the body 20 of the fuel-cell vehicle 11. The fuel gas filler opening 14 is disposed obliquely upward on the bottom of the recess 21. A valve mechanism or a filter is mounted inside the fuel gas filler opening 14 in order to prevent back-flow of the fuel gas. Thus, a fuel gas filler opening cap 23 is attached to the fuel gas filler opening 14 to prevent an operational failure of the valve mechanism or filter clogging due to foreign materials having entered into the fuel gas filler opening 14. The fuel gas filler opening cap 23 is manually attached and detached by a person (for example, a driver or a shop attendant) fueling the vehicle with fuel gas.
In a concaved portion 21, there is provided a lid 26 which is swingably attached to the vehicle body 20 via a hinge mechanism 25 such that the lid 26 swings to change between a closed state for closing the recess 21 and an open state for opening the recess 21. When the lid 26 is in a closed state, the fuel gas filler opening 14 and the fuel gas filler opening cap 23 are closed by the lid 26 to achieve a state wherein the opening is inaccessible from outside, while when the lid 26 is in an opened state, the fuel gas filler opening 14 is exposed and accessible from outside.
In order to fuel a conventional fuel-cell vehicle 11 having the above structure with a fuel gas from the fuel gas supplying device 12 by the method as shown in FIG. 6, the person fueling the vehicle should perform procedures including, at first, releasing the lid 26 to expose the fuel gas filler opening 14, manually removing the fuel gas filler opening cap 23 which is covered over the fuel gas filler opening 14, and connecting the fuel gas filler nozzle 13. After completing filling of the fuel gas, the person should manually attach the fuel gas filler opening cap 23 and finally, close the lid 26.
However, because the lid 26 can be closed (set into a closed state) without attaching the fuel gas filler opening cap 23, and because, as in a gasoline vehicle, the fuel gas filler opening 14 is disposed obliquely upward, there is a disadvantage that foreign material may enter the tank if the fuel gas filler opening cap 23 is accidentally left unclosed, even if a drop-prevention string 24 is attached to the fuel gas filler opening 14 as shown in FIGS. 7 and 8 in order to prevent the cap from being dropped or misplaced when the cap is manually removed. Further, another disadvantage is that, because the fuel gas filler opening cap 23 is tightly attached to the fuel gas filler opening 14 in the structure, it may be difficult to manually attach or remove the cap, so an attachment failure may occur. Therefore, an object of the present invention is to prevent the fuel gas filler opening cap 23 from being accidentally left unclosed and to facilitate attachment and removal of the fuel gas filler opening cap 23.